Three of 2009's best games - Modern Warfare 2, Batman: Arkham Asylum and Uncharted 2 - were all linear affairs, games that proved their excellence by taking a story or situation and guiding you through a wonderfully crafted experience, showing you where to look and when to be dazzled. However, the folks at BioWare, much like their genre rivals Bethesda Softworks, don't play by the rules.

You can spot a BioWare game a mile away as they're generally constructed using the same basic ingredients: a heavy emphasis on a spider-web narrative and dialogue, readily identifiable interesting character tropes and, perhaps most importantly, an obsession with choice and consequence. The studio works to a very simple base formula and then builds from there, adding layer upon layer, choice upon choice. With some games (ahem...Dragon Age: Origins...ahem) that formula is slightly more obvious than in others, but in the hands of skilled developers and master storytellers it becomes so much more than a skeletal theory. On the evidence of Mass Effect 2, Bioware haven't rewritten their working process just yet, but by God they've never been better.

Mass Effect 2 is the Empire Strikes Back of video games, and it's a comparison (one that has surely been made several times now) that works on a number of different levels. It's bigger, better, darker and moodier. The stakes seem bigger, and the startling revelations come thick and fast. The entire game feels more muscular, more powerful, in terms of packing punches to the head, to the heart and to your enemies as well.

Say hello to my little friend!

Much of the latter stems from the gameplay differences: the combat, for example, has been stripped back and then rebuilt and refined to provide a much smoother, more fraught experience. The excellent new cover system actually owes a lot to Army of Two, with a simple tapping of A allowing Shepard to slide coolly behind crates and walls and pillars with ease. It is an overhaul that has been reflected in the level design too, with plenty of things to duck behind, often with varying levels and vantage points, allowing for some incredibly tense firefights.

The cover system is the biggest change, but there are numerous other small tweaks that serve to make the combat in this game a faster-paced, more exciting experience. Gone is the irritating overheating mechanic that plagued the original, replaced by a more traditional reload system. The power wheel returns, but the structure of levelling up and the powers that you can attain has shifted, making each class stand out a little bit more. My Vanguard, for example, could call upon the powers of both the shotgun and biotics, and his class based power - the Biotic Charge - allowed for a teleported body slam that could cross gaps to stun an enemy before rounding things off with some intergalactic buckshot. It means that getting a decent balance in your squad is actually fairly important, particularly on the higher difficulty levels. Gone too are the itemised weapon upgrades, instead extras like incineration and cryo rounds fall under class powers and can be mapped to the shoulder buttons, and you upgrade the effectiveness of your various firearms through research conducted as you progress through.

Good luck getting the red-eye out of THAT family photo!

You might have harboured fears that BioWare, taking on board the combat criticisms of the last game, just swung the other way and made a space shooter, but you'd be wrong. Certain RPG elements such as the constant item reshuffling has been cut to provide a more streamlined experience, but there is no doubt as to what is to be found at this game's heart: a richly drawn, character driven narrative of epic proportions. Just as a sequel should, it expands on everything we saw in the first game, from the rich, deep characterisation to the futuristic Milky Way we came to know and love.

It has been two years since the attack on the Citadel at the end of the original game and much has changed. The game opens with a shocker before turning your appraisal of one of the villainous corporations from the first game on its head. It transpires that entire human colonies are disappearing for no good reason, that a race of alien beings called the Collectors appear to have something to do with it, and that the Citadel Council is systematically denouncing any rumour of the return of the Reapers as lies and falsity. You've pretty much got your work cut out as you go round assembling a team of specialists to go on a suicide mission through the Omega 4 Relay into Collector space to find out what the hell is going on.

But every part of this game drips with character. You'll stave off on saving the galaxy just so you can go rescue one of your crewmates' siblings, or resolve a need for vengeance that still burns inside another. The relationships you build up from checking in with the rest of your team are what drive Mass Effect 2 forward, and all of the members of that team, from spiritual Drell assassin Thane to psychotic biotic Jack, pull you in and make an undeniable case for themselves as why they are there. There are some familiar faces too, a bundle of blasts from the past, and by uploading your character from the original game you can directly affect just how they'll remember you.

Patrick Stewart's daughter was a bit of a black sheep

Finally, the Paragon/Renegade, light vs. dark morality compass returns to truly embed you in this world. Taking a leaf out of Star Wars' book, your character's actions are reflected on your face: follow a conscientious path and you'll appear fresh faced, but start getting your hands bloodied and your rebuilt visage will begin to crack with scarring. Every single thing you do (and indeed have done if you started with a save game carried over from Mass Effect) has a consequence here and affects the reactions of those around you. You'll receive messages and letters from people you've rescued and vengeful condemnations from those you've wronged. You'll be able to step in at key moments during the game's cut-scenes and alter the flow of conversation. Perhaps an obnoxious minion is refusing to talk, well you might just be able to interrupt him mid-way through his defiant speech by kicking him out of a window, cementing your role as a bad-ass.

Criticisms? Well you have to go digging for them to be honest. The interruption options are a brilliant idea, but they are a little too sparse and not quite the finished article just yet, and there are still loading times even if they are overlayed with pretty contextual wireframe readouts. Perhaps, the biggest gripe I have is with the new mining mini-game that you need to undergo in order to research upgrades. It'd be fine if it didn't take so long, if the planets you have to scan were a bit smaller, or if the scan reticle actually moved faster than a stoned tortoise. But if you do get bored you can just hop off and go another unique side quest.

Fans of the series Chuck will no doubt recognise a familiar face

I can't get enough of Mass Effect 2. It's another game that sucks you in until you glance up and realise that you've been playing for ten hours and the birdsong that you can hear heralds dawn, and even then you just figure you'll carry on playing. BioWare has created a galaxy not that far away at all, but it has imbued it with interesting and curious races, vivid characters and boatloads of intrigue. Like any good page-turner, you want to know everyone's backstory and you want to know what happens next. But more importantly, like the best games out there, Mass Effect 2's strength lies in the fact that instead of showing or telling you, it lets you experience and influence the whole ride instead.

Pros:

Improved combat

Wonderful characters

No more Mako or bland side missions!

Cons:

Tedious mining mini-game

Not as much customisation as we'd like

It has to end

The Short Version: Mass Effect 2 is a stunning achievement for BioWare. Not only does it provide a shining example of an ideal sequel, but it further broadens our perceptions of what an RPG should be. The combat is excellent, the graphics are impressive, and the characters are both idiosyncratic and sympathetic. Prepare for it to eat up your life as there's no way you'll just play it once.

2 discs is fine, 360 installs full discs to the hard drive so no problem there especially now the 360 has up to 250gb hard drive.

One thing that puzzles me with the PS3 why no full game installs like the 360 can? instead they make you wait an age just to install a small part of the game that does nothing to help constant disc loading.

Both consoles seem to counter themselves in one way or another when it comes to their loading systems

Yeah it is on 2 discs so Blu-ray might have been useful, but there's not too much back and forth (cough...Lost Odyssey...cough).

I know I'm a huge BioWare junkie and therefore naturally find this game massively effective at pushing all of my gaming buttons, but I'm going to stick my neck out right now and say that 2010 is going to have to produce something pretty damn special for this not to be game of the year come December.

maybe but with Uncharted 1 its damn annoying hearing the disc reading every 2 seconds and Ghostbusters took about an hour start to scratch to install and load...RIDICULOUS when any game in the 360 takes a minute to update!